【例 13-4】与例10.3 Client端应用程序对应的Server端应用程序。程序在4441端口监听，当检测到有客户机请求时，产生一个内为“客户，你好，我是服务器”的字符串输出到客户端。
import java.io.*;import java.net.*;
public class Server{
    public static void main(String args[]){
        ServerSocket server = null;
        Socket you = null;String s = null;
        DataOutputStream out = null;
        DataInputStream in = null;
        try{
            server = new ServerSocket(4441);
        }catch(IOException e1){
            system.out.println(“ERROR:” +e1);
        }
        try{
            you = server.accept();
            in = new DataInputStream(you.getInputStream());
            out = new DataOutputStream(you. getOutputStream());
            while(true){
                s = in.readUTF();
                if(s!=null) break;
            }
            out.writeUTF(“客户，你好，我是服务器”);
            out.close();
        }
        catch(IOException e){System.out.println(“ERROR:”+e);}
    }
}